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Network Troubleshooting

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The former is often referred to as trouble avoidance or pre-emptive troubleshooting ... Time domain reflectometer (TDR) Oscilloscope. Principles of Troubleshooting ... – PowerPoint PPT presentation

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Title: Network Troubleshooting


1
Chapter 13
  • Network Troubleshooting

2
Introduction
  • Look at
  • Avoiding Potential Problems (13.1)
  • Principles of Troubleshooting (13.2)
  • Accessing Key Information Resources (13.3)
  • Handling Common Sources of Trouble (13.4)

3
Avoiding Potential Problems
  • There are two approaches to trouble shooting
  • preventing potential problems through proper
    planning
  • quickly fixing what fails
  • The former is often referred to as trouble
    avoidance or pre-emptive troubleshooting
  • The later is referred to as troubleshooting or
    damage control

4
Avoiding Potential Problems
  • To be effective, both should be used in
    combination
  • Be proactive in managing the environment
  • Know how to effectively troubleshoot any issue
  • Documentation is important
  • It's a tedious job but it is imperative that you
    have proper documentation

5
Avoiding Potential Problems
  • Ensure that users have ongoing access by making
    sure that if something happens you have a backup
    plan
  • Identify the data that should be backed up
  • Determine the backup type and schedule
  • Designate someone to be responsible
  • Be sure the tapes are properly labeled
  • Keep a log

6
Avoiding Potential Problems
  • Security policy should detail hardware and
    software along with some of these areas
  • Clear paths of responsibility and user
    expectations
  • Awareness of privacy issues that may arise
  • A separation of duties, so that total control is
    not left in the hands of a single individual

7
Avoiding Potential Problems
  • Security policy should detail hardware and
    software along with some of these areas
  • Password length, duration, history, and
    complexity requirements
  • A clear policy for the destruction of data
  • Procedures for creating and authorizing accounts
  • Incident response and disaster recovery planning
    policies

8
Avoiding Potential Problems
  • The goal of security is expressed in terms of
  • Confidentiality
  • Integrity
  • Availability
  • These goals can be achieved through creating
    hardware and software standards

9
Avoiding Potential Problems
  • Workstation consistency is often overlooked
  • Installing unauthorized software
  • Downloading infected music and movie files
  • Opening an e-mail message that contain a virus
  • Using weak passwords
  • Not logging off the network when leaving the
    building

10
Avoiding Potential Problems
  • Standards for laptops, personal digital
    assistants (PDAs), Palm Pilots, and Pocket PCs
    may be more difficult to define
  • If these devices are company issued or company
    supported, they must be standardized as well
  • These devices are susceptible to theft because
    they are small and valuable.
  • Many times contain important information about
    the company

11
Avoiding Potential Problems
  • You must also define and document standards for
    new server installations along with guidelines
    for current server configurations
  • The configuration process should start with
    installing only the services necessary for the
    server to function
  • Limit physical access to the server
  • Use Redundant Array of Inexpensive Disk (RAID),
    uninterruptible power supply (UPS) equipment, and
    clustering

12
Avoiding Potential Problems
  • Policies should include provisions for change
    authorization, documentation, and notification
  • Include procedures to be used when hardware,
    software, or storage media is replaced or
    discarded
  • Planning and testing can eliminate corruption or
    data deletion problems
  • Sufficient time must be spent to ensure that the
    transition goes as smoothly as possible

13
Avoiding Potential Problems
  • The following should be considered when creating
    a change in management policy
  • Establish a schedule for changes
  • Make sure users are notified of the changes
  • Conduct proper testing
  • Changes should be scheduled during off hours

14
Avoiding Potential Problems
  • Documentation is critical
  • Before actually deploying the change, testing
    should be conducted
  • Testing should be well documented
  • A rollback strategy should be part of every
    change plan

15
Avoiding Potential Problems
  • Thorough documentation is a necessary part of an
    administrator's job
  • Document everything you do and be as detailed as
    you can
  • Documenting is particularly important because of
    the impact it can have on business if legal
    action is involved
  • All documents should be kept in both hard- and
    soft-copy form

16
Avoiding Potential Problems
  • Your network documentation should include these
    components
  • Policies and procedures
  • Network history
  • Network map
  • Cable diagrams and layouts
  • Contact list
  • Equipment list

17
Avoiding Potential Problems
  • Your network documentation should include these
    components
  • Computer and network device configuration
  • Software and its configuration
  • Network address list
  • Software licensing information

18
Avoiding Potential Problems
  • Pre-emptive troubleshooting is also called
    trouble avoidance
  • It will save time and may help save data when
    problems arise
  • Pre-emptive troubleshooting can also prevent
    additional expense and downtime while trying to
    figure out what happened after a failure

19
Avoiding Potential Problems
  • The ISO defines five pre-emptive troubleshooting
    network management categories
  • Accounting management
  • Configuration management
  • Fault management
  • Performance management
  • Security management

20
Avoiding Potential Problems
  • The measure of normal network activity is known
    as a baseline
  • This gives you a point of reference when the
    network goes awry
  • Baselining should be done for both network and
    application processes
  • The allows you to determine whether you have a
    hardware or software issue

21
Avoiding Potential Problems
  • There are tools can be used to gather network
    information
  • Event Viewer allows you to audit certain events
  • Task manager can be used to end processes or
    applications that get hung up without having to
    reboot the machine
  • Auditing is the process of tracking users and
    their actions on the network

22
Avoiding Potential Problems
  • Keep in mind that auditing uses system resources
    and space
  • The Performance console is used for tracking and
    viewing the utilization of operating system
    resources
  • A network monitor can be used to capture network
    traffic and generate statistics for creating
    reports

23
Principles of Troubleshooting
  • Troubleshooting requires skill
  • These skills are acquired through experimentation
    and experience
  • You cannot learn the resolution to every problem
    that exists
  • You can, however, learn a methodology to find and
    diagnose nearly every problem in a systematic and
    logical manner

24
Principles of Troubleshooting
  • The following are the most common network
    problems
  • User error
  • Physical connections
  • System needs a reboot
  • If these steps don't help, then it's time to move
    on and try other troubleshooting options

25
Principles of Troubleshooting
  • Research on problem solving and reasoning is
    fundamental to understanding troubleshooting
    skills
  • You can choose from several different
    methodologies of troubleshooting
  • These give us guidelines for logical solving
    problems using a step-by-step process

26
Principles of Troubleshooting
  • The first step is to determine the scope of the
    problem by identifying the symptoms
  • The next step is to collect specific information
    about the problem at hand
  • Once you have the pertinent information, then the
    scope is determined
  • Begin to isolate the problem by testing each of
    the causes, starting with the most obvious first

27
Principles of Troubleshooting
  • Attempt to re-create the problem
  • Make only one change at a time
  • Test each change
  • Don't be afraid to ask for help
  • Read the documentation that came with the
    hardware or software
  • Don't forget about the obvious

28
Principles of Troubleshooting
  • Creating a Hardware Toolkit
  • Crossover cable
  • Hardware loopback adapter
  • Tone generator
  • Cable tester or cable checker
  • Voltmeters
  • Time domain reflectometer (TDR)
  • Oscilloscope

29
Principles of Troubleshooting
  • Creating a Software Toolkit
  • Ping
  • Netstat
  • Nbtstat
  • Traceroute
  • Network monitors
  • Protocol analyzer

30
Accessing Key Information Resources
  • One of the best places for troubleshooting a
    problem is the manufacturer's Web site
  • Subscription services such as TechNet can be used
    to obtain a wealth of information
  • Vendor-provided CDs should be one of the first
    places you go to look for information
  • Look at the readme.txt file even before the
    product is installed

31
Accessing Key Information Resources
  • Resource kits are another excellent source of
    information about your operating system
  • Call the vendor and open up a technical support
    incident to solve the problem
  • If it is a known issue the vendor may have
    documented fixes available

32
Accessing Key Information Resources
  • Have the following information ready to assist
    the support department
  • The operating system you are running
  • Service packs that are installed
  • Version numbers of hardware and software
  • Serial numbers
  • Detailed account of the problem and
    troubleshooting steps you have taken

33
Accessing Key Information Resources
  • Other excellent sources of information are
    periodicals and white papers
  • Many new magazines and periodicals are introduced
    each year, some of them deal with specific
    computing environments
  • Besides white papers and periodicals, dont
    forget to keep a couple of good reference books
    handy, especially when you first start out

34
Handling Common Sources of Trouble
  • Not all problems will be easy to fix
  • The two most common causes for data not moving
    reliably are
  • A physical connection breaks such as the cable
    being unplugged or broken
  • A network device is not working properly

35
Handling Common Sources of Trouble
  • The majority of networking problems occur at the
    Physical layer of the OSI model and include
    problems with
  • cables
  • connectors
  • NICs
  • Check cabling and connections first during your
    network troubleshooting process

36
Handling Common Sources of Trouble
  • Power problems will crop up in various ways
  • One of the most obvious is when power strips are
    daisy chained together
  • The devices will not get enough power
  • The other end of the spectrum is that this will
    occasionally trip the circuit breakers or start a
    fire

37
Handling Common Sources of Trouble
  • Power not properly conditioned, can have
    devastating effects on equipment
  • Noise
  • Spikes
  • Surges and overvoltages
  • Sags and brownouts
  • Blackouts

38
Handling Common Sources of Trouble
  • Always connect your sensitive electronic
    equipment to
  • power conditioners
  • surge protectors
  • for the best protection an uninterruptible power
    supply (UPS)
  • The UPS powers the computer so that you can take
    action without data loss

39
Handling Common Sources of Trouble
  • There are basically three different types of
    devices that are classified as UPSs
  • Standby power supply (SPS)
  • Hybrid or ferroresonant UPS systems
  • Continuous UPS
  • Never plug a printer into a UPS
  • Power problems cannot be eliminated but the
    damage can be minimized or prevented

40
Handling Common Sources of Trouble
  • A software upgrade can cause issues on the system
    even though you tested the upgrade
  • You should be prepared to rollback or reverse the
    process.
  • This process is also referred to as backleveling
  • Most often the best source of help when a problem
    occurs is the manufacturer's documentation

41
Handling Common Sources of Trouble
  • You will also have to provide for a backup plan
    in the event a hardware upgrade doesn't go as
    planned
  • It is important not the discard the old device in
    the event the upgrade causes issues
  • This applies to the drivers that may be necessary
    as well

42
Handling Common Sources of Trouble
  • The complexity of network topology and
    communication equipment has become more and more
    sophisticated
  • Performance management as well as response time
    management is more difficult
  • Sometimes you will find that for an unknown
    reason the network performance begins to suffer

43
Handling Common Sources of Trouble
  • Here are some avenues for you to consider when
    there are issues with performance
  • Change is the biggest factor that can cause poor
    network performance
  • Another big factor that affects network
    performance is playing games or downloading music
    and movie files

44
Handling Common Sources of Trouble
  • Here are some avenues for you to consider when
    there are issues with performance
  • Sometimes applications have memory leaks or a new
    version may be bloated or have an improperly
    programmed query function
  • Adding new electrical equipment may have a
    negative effect on the network

45
Handling Common Sources of Trouble
  • Here are some avenues for you to consider when
    there are issues with performance
  • Adding new hardware such as additional servers or
    workstations may cause performance to decrease
  • Other changes in workload or workplace behavior,
    including adding more users, could affect
    performance
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